The real CPI? The one that matters? Yes, the Cappuccino Price Index!
Unfortunately it doesn't seem to be updated very often, but I suppose a lot of research has to be done which must be time-consuming.
I wonder if the results ought to be sorted by postcode. Every time I buy coffee I seem to pay at least, and often more than, the average. Where are those "good-value" coffees at less than the average price? Perhaps we need a "coffee watch" site as happens with petrol - or would this offend the ACCC?
I also wonder where the all-pervasive coffee cards fit in to the calculations? Does this index take account of the fact that, if you're loyal, every 6th or 7th coffee is "free"? Or are these cards disregarded on the basis that most people are like me and have a pile of cards with two holes stamped and can never find the right card when I return and have start all over again with a new card?